1. Field of the Invention
This invention relates to lift trucks, and more particularly to a motor-driven hydraulic system for a power steering unit of a battery powered lift truck.
2. Description of the Prior Art
Lift trucks, and in particular higher volume range battery powered lift trucks, have generally not made use of power steering units because of the high costs of installing and operating such units and because of the heavy drain on the power of the battery.
Part of the expense is the requirement of an additional electric motor and its controls for use just for power for the power steering unit. When the vehicle is in operation, the additional electric motor and pump must be driven at full speed at all times, whether or not there is a demand for the fluid for steering purposes. It is necessary that the continuous pumping of oil through the open center power steering unit be maintained readily available for instant steering. The additional electric motor and pump affects approximately a ten percent drain on the battery capacity for the purposes of operating the power steering unit.